cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-4 of 4 results.

A127379 Signature-permutation of Callan's 2006 bijection on Dyck Paths, mirrored version (A057164-conjugate).

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 8, 7, 9, 10, 11, 13, 12, 14, 15, 19, 22, 21, 16, 20, 17, 18, 23, 24, 25, 27, 26, 28, 29, 33, 36, 35, 30, 34, 31, 32, 37, 38, 39, 41, 40, 51, 52, 60, 64, 63, 56, 62, 58, 59, 42, 43, 53, 54, 55, 44, 61, 45, 46, 47, 57, 48, 50, 49, 65, 66, 67, 69, 68, 70, 71
Offset: 0

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Author

Antti Karttunen, Jan 16 2007

Keywords

Comments

It's much easier to implement Callan's 2006 bijection for S-expressions if one considers a mirror-image of the graphical description given by Callan (on page 3). Then this automorphism is just RIBS-transformation (explained in A122200) of the automorphism A127377 and Callan's original variant A127381 is obtained as A057164(a(A057164(n))).

Crossrefs

Inverse: A127380. a(n) = A057164(A127381(A057164(n))). The number of cycles and the number of fixed points in range [A014137(n-1)..A014138(n-1)] of this permutation are given by A127384 and A086625 shifted once right. The maximum cycles and LCM's of cycle sizes begin as 1, 1, 1, 2, 4, 4, 8, 8, 8, 8, 16, 16, 16, 16, ... A127302(a(n)) = A127302(n) holds for all n. A127388 shows a variant which is an involution.
Differs from A073289 and A122349 for the first time at n=54, where a(n)=54, while A073289(54) = A122349(54) = 61.

A127381 Signature-permutation of Callan's 2006 bijection on Dyck Paths.

Original entry on oeis.org

0, 1, 2, 3, 4, 5, 6, 8, 7, 9, 10, 11, 13, 12, 14, 15, 19, 22, 18, 16, 21, 17, 20, 23, 24, 25, 27, 26, 28, 29, 33, 36, 32, 30, 35, 31, 34, 37, 38, 39, 41, 40, 51, 52, 60, 64, 46, 47, 59, 50, 49, 42, 43, 56, 63, 55, 44, 58, 45, 48, 53, 62, 54, 61, 57, 65, 66, 67, 69, 68, 70, 71
Offset: 0

Views

Author

Antti Karttunen, Jan 16 2007

Keywords

Comments

This automorphism is much easier to implement for S-expressions when viewed as a A057164-conjugate of A127379. See the comments in the latter entry.

Crossrefs

Inverse: A127382. a(n) = A057164(A127379(A057164(n))). The number of cycles and the number of fixed points in range [A014137(n-1)..A014138(n-1)] of this permutation are given by A127384 and A086625 shifted once right. The maximum cycles and LCM's of cycle sizes begin as 1, 1, 1, 2, 4, 4, 8, 8, 8, 8, 16, 16, 16, 16, ...

A127383 Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A127377/A127378.

Original entry on oeis.org

1, 1, 1, 2, 6, 15, 46, 141, 446, 1427, 4722, 15884, 54224, 187380
Offset: 0

Views

Author

Antti Karttunen, Jan 16 2007

Keywords

Crossrefs

A175137 Irregular triangle T(n,k) read by rows: number of orbits of size 2^k on Dyck n-paths.

Original entry on oeis.org

1, 2, 3, 1, 6, 2, 1, 12, 7, 4, 26, 23, 11, 2, 59, 71, 41, 8, 138, 224, 151, 30, 332, 709, 550, 114, 814, 2253, 1993, 406, 16, 2028, 7189, 7211, 1564, 64, 5118, 23045, 26221, 6010, 240, 13054, 74213, 95583, 23062, 912, 33598, 239979, 349145, 88530, 3504, 87143
Offset: 1

Views

Author

R. J. Mathar, Feb 21 2010

Keywords

Examples

			Triangle starts at row n=1
1;
2;
3,1;
6,2,1;
12,7,4;
26,23,11,2;
59,71,41,8;
138,224,151,30;
		

Crossrefs

Cf. A127384 (row sums).

Programs

  • Maple
    Fx := proc(k) local ak ; ak := (2*x)^(2^k+1) ; (1-ak-(1-4*x+(ak*x*(2-ak))/(1-x))^(1/2))/(2*x-ak) ; end proc: ff := [] : for k from 0 to 5 do ff := [op(ff), taylor(Fx(k),x=0,18)] ; end do : F := proc(n,k) global ff ; coeftayl(op(k+1,ff),x=0,n) ; end proc: T := proc(n,k) global ff ; if k = 0 then F(n,0) ; else (F(n,k)-F(n,k-1))/2^k ; end if; end proc: for n from 1 to 17 do for k from 0 to 5 do if T(n,k) <> 0 then printf("%d,",T(n,k)) ; fi; end do ; printf("\n") ; end do ;
Showing 1-4 of 4 results.